Uniform Acceleration of the Car v(m/s) 5 t (s) 2 10 15 20 25 4 6 8 Slope = change in velocity = Δv change in time Δt 10 Four Kinematic Equations Vf = Vi + at 2 x = Vit + ½ at 2 2 Vf = Vi + 2ax x = ½ (Vf + Vi)t CL: Solve-Pair-Share 1) A car accelerates at 5.0 m/s2 from rest. After 7.0 s, (a) what is its velocity? (b) what is the distance covered? CL: Solve-Pair-Share 2) A race car travels on a straight racetrack with a forward velocity of 60 m/s and slows at a constant rate to a velocity of 33 m/s over 22 s. How far does it move during this time? CL: Solve-Pair-Share 3) A car accelerates at a constant rate from 16 m/s to 24 m/s while it travels a distance of 138 m. How long does it take to achieve the final speed? CL: Solve-Pair-Share 4) A jet aircraft being launched from an aircraft carrier is accelerated from rest along a 94-meter track for 2.5 s. What is the launch speed of the jet? CL: Solve-Pair-Share 5) Upton Chuck is riding the Giant Drop at Great America. If Upton free falls for 2.60 seconds, what will be his final velocity and how far will he fall? CL: Solve-Pair-Share 6) A car starts from rest and accelerates uniformly over a time of 5.21 seconds for a distance of 110 m. Determine the acceleration of the car. CL: Solve-Pair-Share 7) At a sports car rally, a car starting from rest accelerates uniformly at a rate of 9.0 m/s2 over a distance of 100m. The time to beat is 4.5 s. Does the driver do it? If not, what must be the acceleration to do so? Coin versus Paper Free Fall When a falling object is free from air resistance and falls under the influence of gravity alone, it is in state of free fall. Galileo Galilei discovered 400 years ago that neglecting air resistance, all objects in free fall have the same acceleration. Free Fall The acceleration of a free falling body is constant. It is called acceleration due to gravity (g). Acceleration of Falling bodies • As an object falls freely, its speed increases at a constant rate. • It undergoes uniform acceleration. Pair-Share • Just like an object in free fall, there are times in your life when you feel down. What do you do during these times? How do you motivate yourself to stay positive and persevere to reach your goals?
